Radical additions to fluoro-olefins. Photochemical mono-fluoroalkylation and sequential bis-fluoroalkylation of oxolane

Abstract Oxolane was fluoroalkylated by its photoadditions under atmospheric pressure. Monofluoro-alkylations were carried out with hexafluoropropene ( 1 ) and perfluorovinyl ethers C 3 F 7 O-[CF(CF 3 )CF 2 O] n -CF = CF 2 ( 24 , n = 0–2) by direct photoexcitation of the olefins to give high yields of addition products 9–12 (81–94%). The reactions were completely regioselecti ve at the oxolane molecule and almost completely regioselective (93–99%) at the double bond of fluoro-olefins; no bis-fluoroalkylated oxolanes were detected. The completely selective introduction of a second fluoroalkyl into position 5 of the oxolane molecule was accomplished by acetone-sensitised photoaddition of 2fluoroalkylated oxolanes 9,10 to fluoro-olefins 1 and 2 . Byproducts from reactions of the dimethylketyl radical which is formed in the initiation step were isolated and have given some evidence about the reaction mechanism that is discussed.